SvelteKit full-stackFull-stack Svelte with adapters for every target
SvelteKit is the official Svelte meta-framework — file-based routing, server-only load functions, progressive form actions, and adapters that deploy to Vercel, Cloudflare Workers, Node, or static hosting. Fast by default, flexible by design.
SvelteKit is the official full-stack framework for Svelte — providing file-based routing, server-only load functions, progressive form actions, and deployment adapters for every major platform. It compiles your Svelte components to minimal JavaScript while giving you a production-ready framework with SSR, streaming, code splitting, and edge deployment out of the box. SvelteKit's progressive enhancement philosophy means forms and navigation work without JavaScript and enhance when available. Combined with Svelte 5's runes for reactivity and adapters for Vercel, Cloudflare Workers, Node, or static output, SvelteKit is the complete platform for building fast, accessible web applications.
Quick start
npx sv create my-app
cd my-app
npm install
npm run devRead the full documentation at svelte.dev/docs/kit
File-based routing
Routes defined by the filesystem — +page.svelte, +layout.svelte, +error.svelte. No config, no magic strings.
Server load functions
+page.server.ts load functions run exclusively on the server — fetch data, read databases, no leaking secrets.
Progressive form actions
Form actions handle mutations on the server with progressive enhancement — works without JS, enhanced when available.
Adapter-agnostic deployment
Single adapter swap to target Vercel, Cloudflare Workers, Node.js, Netlify, or fully static output.
Streaming & defer
Stream slow data with SvelteKit's `defer` — fast shell renders immediately while slow promises resolve.
Hooks & middleware
Server hooks for auth, logging, and request transformation — handle API requests and page loads in one place.
Why it's hard
Load function data flow patterns
Understanding when to use +page.server.ts vs. +page.ts load functions, how data cascades through layouts, and when invalidation triggers requires careful study of SvelteKit's data flow model.
Form action error handling
SvelteKit's progressive form actions are powerful but handling validation errors, redirect flows, and multiple actions per page introduces patterns that differ from typical SPA form handling.
Adapter-specific deployment gotchas
Each deployment adapter (Vercel, Cloudflare, Node, static) has different capabilities and limitations — edge function size limits, environment variable access, and API behavior vary per target.
Svelte 5 runes + SvelteKit integration
Migrating SvelteKit apps to Svelte 5 runes while maintaining proper SSR, load function patterns, and store compatibility requires understanding both the new reactivity model and SvelteKit conventions.
Best practices
Use +page.server.ts for data that touches secrets
Server-only load functions never send their code to the client. Default to +page.server.ts and only use +page.ts (universal load) when you need the data during client-side navigation without a server round-trip.
Leverage form actions for mutations
SvelteKit's form actions handle POST requests with progressive enhancement — they work without JavaScript and enhance with client-side behavior. Prefer them over manual fetch() for form submissions.
Use streaming for slow data
Return promises from load functions to stream slow data while rendering the fast parts of the page immediately. Users see content sooner without waiting for every database query.
Implement hooks for cross-cutting concerns
SvelteKit's handle hook in hooks.server.ts runs on every request — use it for auth checks, request logging, security headers, and locale detection in one centralized location.
Frequently asked questions
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